


Poisoned

by VictoriaAGrey



Category: Supernatural
Genre: Demon Blood Addiction, Demon Dean, Demon!Dean feeds Sam demon blood, M/M, Manipulation, Sam doesn't react to Dean's blood as he planned, Transformation, held captive, powerful sam
Language: English
Status: Completed
Published: 2014-10-11
Updated: 2014-10-11
Packaged: 2018-02-20 18:38:10
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,978
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2438747
Author URL: https://archiveofourown.org/users/VictoriaAGrey/pseuds/VictoriaAGrey
Summary: <blockquote class="userstuff">
              <p>When Demon Dean feeds his blood to Sam, Sam undergoes a horrible transformation.</p>
            </blockquote>





	Poisoned

**Author's Note:**

> Prompted by the preview for SPN 10x02, where Dean cuts open his hand and says to Sam, "What I'm gonna do to you Sammy, you have no idea."
> 
> *cough* Did they mean for that to sound as Wincest-y as it did!? *cough*

Dean glared daggers into his little brother as he resolutely stared back; fear tempered by the knowledge that even as a demon poisoned by the Mark of Cain, Dean wouldn’t kill him. Privately Dean acknowledged that it was true, his human psychology too strong to defy in the case of his brother, but that didn’t mean he was entirely _safe_. A thrill, not unlike that of one about to add another conquest to their name, washed through his system knowing that he now had the power to drag the single person he could not live without into the depths where his mind and badly mangled soul resided. The pull to do that having been a wish long before Stanford lured him away more than a decade ago.

“Dean, we can fix this,” Sam insisted, for what must be the hundredth time, as his arms pulled at the ropes binding him to the wooden chair he was tied to.

“I don’t wanna be fixed.”

“I’m not talking to the demon part of you. I am talking to my brother. My brother would never want this for himself.”

It took every shred of will power in him to not roll his eyes at that plea. At some point, he could have honestly replied that no, this isn’t something he wanted for himself, but not anymore. What Sam didn’t know, what nobody else besides Dean did, is that the Mark of Cain didn’t cancel out who he was in favor of its own engrams. The Mark persuaded rather than influenced, its clever sway registering at an almost physical level. Thick tendrils of temptation spun up his arm and neck to entrench themselves in his brain, releasing a flood of what felt like viscous fluid that seeped into every crevice. Those dark, heavy waters acted as a truth serum that gently coaxed deeply embedded truths within his mind to the surface to be recognized.

The first one he saw, the one that made his human predilections cry in horror, leaving a note behind begging Sam to let him go before he fled, was that he would do anything in his power to keep Sam safe. At first it didn’t seem like news to him, he had already killed without remorse for him and sold his soul to ensure his continued existence, but that wasn’t where the revelation ended... it was where it began. The bald faced truth that was plucked from a place he never allowed himself to go was that he would keep Sam safe even at the cost of destroying him; fragmenting and decimating every part of Sam that risked his own survival. Thinking of this fact now, he was no longer filled with terror, but righteousness.

Sam may not _feel_ safe now, but there was no place safer in the world for him in that moment than being tied to a chair in the middle of an abandoned dive bar accompanied by his demonic brother.

“Oh, Sammy,” Dean taunted with a chuckle. “You don’t know what I want.”

“Dean, please. I know you’re in there and I need you to listen. This isn’t you talking and these aren’t your thoughts. I can help you.”

“Fucking hell.”

“Don’t allow me to be dismissed! Do not shut me out! Hear what I have to say. I have the cure. This can all be undone. It can all end tonight.”

The Mark’s poison, sitting at a low simmer, boiled at the thought of losing his newly acquired ability to save Sam from himself. Rage nearly drove him forward, First Blade first, in order to make him pay for such an ignorant comment. All that stopped him was knowing that Sam did not yet know what he was asking of him and digging the tip of the Blade into his bottom lip until it bled, droplets rolling down his chin. The sting and the tangy iron taste of his own blood reminded Dean of why they were there, of how to keep Sam safe forever, and he decided that the time for talking was over.

Fissions of panic cracked Sam’s voice when he saw Dean drag the Blade across the Mark, splitting the skin so it bled liberally. “What are you doing?”

“You know exactly what I’m doing,” he responded as he circled Sam, his prey, to allow him to see the red blood tinged with black that spilled down his arm.

“It won’t work.”

“Yes, it will. That’s why you’re scared. You can still feel the potential in you to do this and I’m gonna make it happen.”

“D- De- Dean, don’t do this. Please.”

“I’m sorry, Sam, but I have to keep you safe.”

Swiftly turning to face Sam, Dean threaded his fingers into his long hair to yank his head back, taking advantage of his mouth that opened to cry out in pain to plant his bleeding arm over his open orifice. Teeth sank into his arm as a terrified Sam struggled to escape his bonds and the tainted blood pouring into his mouth. The fight or flight response triggered in him, the fear of turning into a monster of his own creation too great to ignore, kept him from stilling and accepting his fate. Dean bit into his already split lip to fight the urge to remove his arm from Sam’s vicious teeth, willing to lose his entire damn arm if it meant saving Sam. He was so close he could feel it. Just a little longer and...

Sam’s teeth loosened their grasp on Dean’s arm as he began coughing, likely choking on the blood in his mouth. Excess blood seeped out the sides, sliding down his cheeks and chin and that’s when Dean saw victory; the upwards bob of his Adam’s apple as he swallowed. Not willing to risk it being a rouse, Dean kept his arm where it was, but did move it so there was enough room for Sam to breathe through his nose. A desperate whine came from Sam before Dean felt his tongue roughly trace over the cut as he started to suck.

Dean moaned at the sensation of Sam sucking on his self-inflicted wound, drinking and swallowing his blood in earnest, greedy for every drop he could get. He felt like he wasn’t simply giving Sam blood, but _feeding_ him _power_. Stars danced before his eyes and his knees went weak as blood drained from his head into Sam and below his belt. Never had he felt so drunk and so alive.

Tightly shut eyes cracked open, Sam making eye contact with Dean with the first time since he last begged Dean for mercy. His pupils were blown wide and they trailed down Dean’s face, resting on his lips to follow a drop of blood. Slowly taking his sore, bloodied arm away from Sam, Dean followed his impulse to put his lips within reach of Sam’s. Sam’s breath smelled richly of iron as it billowed across his face. It was with a gentle ease, so removed from the frantic drinking seconds before, that Sam took Dean’s bleeding lip between his own, rolling it so it would give him its last drops before swelling closed. When Sam released him, Dean keened at the loss of sensation.

Stepping back to observe his work, he watched Sam loll is head to the side, likely wired and exhausted by taking in so much demon blood in one go. Blood was _everywhere_ ; all over his face, in his hair, down his neck, soaking his shirt. Dean knew he couldn’t look much better as he looked down at his own filthy arm that was entirely colored by black-infused blood. The smirk sneaking onto his face froze when he heard Sam gasp weakly for air.

“Sam,” Dean called, allowing his voice to show some of the worry he felt. “Sam!?”

Before he could take a step back towards him, Sam’s chest curved into the air as he cried out in agony. The only thing keeping him in the chair were the ropes tightly secured around his arms and legs as his body seemed to _vibrate_ in place. Quakes unrelentingly wracked his entire body as an angry red color permeated his white skin. Without warning, Sam threw his head forward and screamed at the top of his lungs as an intense burst of energy emanated from him, powerful enough for Dean to see before it threw him across the bar and into the far wall.

Quickly scrambling in his dazed state, Dean got to his feet in time to see Sam writhing on his stomach, the ropes which had tied him to the chair in threads across the warped wood floor. Growls and pants of pain kept coming from him and Dean fast realized how out of his league he was. All this was supposed to do was help Sam reclaim his powers; make him invincible so they could conquer this God forsaken world and Hell below together. A bone-deep fear took over Dean’s faculties that instead of saving his brother, he had killed him.

Dean continued watching in shock and disgust as his brother transformed into something wholly not human. Ripples across his red skin left behind a scaly texture and his fingers elongated to a grotesque length, growing nails Nosferatu would envy. Ivory white teeth were shoved out of his gums to be replaced by sharper, longer ones. Just when the transformation seemed to be winding down, Sam got to his knees, arched his chest, and roared, a guttural sound reminiscent of the balrog’s in The Lord of the Rings, while thick, black goat horns sprouted from the crown of his skull.

Paralyzed into inaction, Dean didn’t move a muscle as Sam slowly stood and turned to look in his direction. What had been purely Sam moments ago was now a hybrid of sorts, every nightmare imaginable coalescing into a monster that laid waste to most physical traces of Sam, his face still distinctly his but _not_ , red scales now replacing what had been clear, white skin. The new Sam walked towards him after a few moments of observation, a pronounced reptilian smoothness in his gait.

The first piece of information Dean took in about this new creature before him was that he didn’t smell like Sam; in fact, he didn’t smell like anything at all. Secondly, his eyes were no longer blue, but demon black flecked with golds and reds. Up close, the crawling sensation that trilled up Dean’s spine was almost easily ignored in the face of his bizarre beauty. His height was all Sam’s, but the horns gave him the appearance of being that much taller, towering menacingly over Dean.

Lifting a graceful scaled hand, Sam ran the palm of it across his new teeth until they broke skin. Rather than blood, clear liquid, the consistency of molasses, bloomed out of the wound. Sam raised it and placed it over Dean’s mouth, Dean too transfixed by the sight to protest, and flexed his fingers so long nails dug into the flesh of his face. The liquid coming out of his hand had a crisp taste to it, as refreshing and delicious as iced water on a hot summer day. As he swallowed Sam’s blood, it felt as if liquid nitrogen had been poured down his throat and into his stomach. The chill was borderline painful, but he felt he was being replenished in a sense as he continued to drink. Sam closed his eyes and sighed when Dean licked the torn flesh, pulling it away after what he deemed to be enough.

A familiar tug on Dean’s insides made his clothes - his pants - feel utterly confining. He exchanged a heated glance with Sam before he leaned forward and commanded in a gentle purr, with a voice that was totally his own, “We got work to do.”

**Author's Note:**

> Kudos if you know why I chose that quote to be the final line of this fic!
> 
> As is my usual send off in my fanfics, I hope you enjoyed your read and feel free to come at me on my Tumblr, [mycroft-silently-judges-you](http://mycroft-silently-judges-you.tumblr.com)! I'd love to hear from you!
> 
> This my first one-shot in the SPN fandom. Be gentle! <3


End file.
